Mechanical properties and microstructure of ultra-lightweight cement composites with fly ash cenospheres after exposure to high temperatures

Huang, Zhenyu; Krishnan, Padmaja; Li, Shan; Liew, J.Y. Richard

doi:10.1016/j.conbuildmat.2018.01.009

Cited by 90 publications

(41 citation statements)

References 38 publications

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“…After 48 h, the specimens are damaged and peeled off and a large amount of coarse aggregate are peeled off from the cement paste, and the interface adhesion force is attenuated or even lost. The compressive strength decreases by more than 70% after treatment of 800 • C and the bearing capacity is basically lost after exposure to 1000 • C [42,43]. porous materials result in the appearance of a large number of long and wide cracks on the surface of the specimens.…”

Section: Microscopic Analysismentioning

confidence: 99%

Performance Degradation and Microscopic Analysis of Lightweight Aggregate Concrete after Exposure to High Temperature

2020

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This study analyses the deterioration of mechanical properties in lightweight concrete after exposure to room temperature (20 °C) and high temperature, i.e., up to 1000 °C, including changes in visual appearance, loss of mass, and compressive strength. All-lightweight shale ceramsite aggregate concrete (ALWAC) and semi-lightweight shale ceramsite aggregate concrete (SLWAC) are prepared using an absolute volume method to analyse the relationships between relative ultrasonic pulse velocity, loss rate of compressive strength, damage degree, and temperature levels. Our results show that, under high temperature, the lightweight aggregate ceramsite concrete performs better compared to normal concrete. After exposure to 1000 °C, the ALWAC shows a strength loss of no more than 80%, while the normal concrete loses its bearing capacity, with a similar strength loss as the SLWAC. Furthermore, the relative ultrasonic pulse velocity and damage degree are used to evaluate the effects of high temperature on the concretes, including the voids and cracks on the surface and inside of the specimens, which induces the deterioration of mechanical properties and contributes to the thermal decomposition of the cementing system and the loss of cohesion at the aggregate interface. Based on internal structure analyses, the results from this study confirm that the lightweight aggregate concrete shows a high residual compressive strength after exposure to the high temperature.

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Section: Microscopic Analysismentioning

confidence: 99%

Performance Degradation and Microscopic Analysis of Lightweight Aggregate Concrete after Exposure to High Temperature

2020

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“…A series of works have shown the high efficiency of use as lightweight aggregates for cement systems [5][6][7][8][9][10], including building mortars and dry building mixtures of hollow microspheres -glass and aluminosilicate. The spherical shape of the aggregate provides greater plastic properties of the mixes and higher compressive strength.…”

Section: Problem Statementmentioning

confidence: 99%

Properties of lightweight dry masonry mixtures for winter conditions

Semenov

2019

E3S Web Conf.

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The construction of building envelopes using effective small-piece elements requires the use of lightweight masonry mortars, obtained, as a rule, from dry mixtures. One of the most effective ways to obtain such mortars is the introduction of hollow ceramic microspheres into their composition as a lightweight filler. For the climatic conditions of the Russian Federation, it is relevant to use dry masonry mixtures in the winter version, which gain strength at negative temperatures. The main purpose of this work was the development of optimal compositions of modified dry masonry mixes with hollow ceramic microspheres and antifreeze additives for use in winter conditions. Determination of the main properties of dry mixes and masonry mortars was carried out according to standard methods. X-ray diffraction and scanning electron microscopy were used to research of the microstructure and phase composition of the materials. As a result of this research, the compositions of the lightweight dry masonry mixtures for winter conditions were developed. The main properties of the mortar mixtures and mortars were determined and structure and composition of new phases of cement stone were studied as well.

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“…By so doing, the escape of cement into the low-pressure zones can be prevented. However, the sheath made of the lightweight cement slurry has a low early compressive strength and obtains the required property at a later bonding time [34][35][36][37][38][39][40][41][42]. The waiting time for geophysical measurements after cement injection and bonding is nowadays reduced, and so is the time required to carry out further works after cementing.…”

Section: Introductionmentioning

confidence: 99%

Recipe of Lightweight Slurry with High Early Strength of the Resultant Cement Sheath

Kremieniewski

2020

Energies

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Admixtures of mineral or waste filling materials are used to reduce slurry density. However, the sheath made of lightweight cement slurry has low mechanical performance at the initial bonding time. The required strength is achieved later. This is the main problem when evaluating the cement bond logging. The waiting time for geophysical measurements after injecting and bonding of cement is nowadays increasingly shortened. This is forced by economic factors. Too early geophysical measurements may result in obtaining a false indication of the cement bond logging. The lack of cement or partial bonding, despite the presence of slurry in the annular space is then found. The slurry developed by the author achieves high compressive strength after a short bonding time. Reducing the amount of water in the slurry resulted in a lowered filtration value. This is important in preventing gas migration after the cementing. The designed slurry also reaches the value of 3.5 MPa in a short time. This allows for an earlier commencement of a well drilling. The use of said slurry improves the effectiveness of the well sealing and makes it possible to obtain a reliable knowledge of the bond logging.

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Mechanical properties and microstructure of ultra-lightweight cement composites with fly ash cenospheres after exposure to high temperatures

Cited by 90 publications

References 38 publications

Performance Degradation and Microscopic Analysis of Lightweight Aggregate Concrete after Exposure to High Temperature

Performance Degradation and Microscopic Analysis of Lightweight Aggregate Concrete after Exposure to High Temperature

Properties of lightweight dry masonry mixtures for winter conditions

Recipe of Lightweight Slurry with High Early Strength of the Resultant Cement Sheath

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